1. Field of the Invention
This invention relates generally to bicycle wheels, and is more particularly concerned with a contractible rim for receiving a non-stretchable tire.
2. Discussion of the Prior Art
The commonly used rim and tire for bicycles includes a generally rigid rim held by a plurality of spokes extending from a central hub. Since the rim is rigid, one must stretch the tire, and tube when used, to place the tire on, or remove the tire from, the rim. The tire is necessarily quite tough and difficult to stretch, so prying-type tools are required to mount and demount a tire.
There have been many efforts to improve the bicycle rim by breaking the rim in its periphery, and allowing sections of the rim to hinge inwardly, or for the rim to assume a helical shape with a smaller outer circumference than the wheel when in use. The helical shape is disclosed in U.S. Pat. Nos. 1,337,652, 1,455,684, 1,535,398, 1,611,046, and 1,667,243 for example. The hinged sections are shown in U.S. Pat. Nos. 1,811,109, 1,855,000, 1,887,984, 1,931,229, and 2,469,629, for example.
The prior art rims tend not to have spokes at the time the rims are contracted; and, the rims are rather severely distorted on contraction. Additionally, if there is a tube on the rim at the time of contraction, the end of the rim is likely to damage the tube as the rim moves inwardly, out of the circular path of the normal rim.